This program grant is concerned with biochemical aspects of perinatal life. It emphasizes two main biological areas: 1) cellular and organ behavior, 2) organismal growth and development. The primary objective is to study the effect of various environmental stimuli on different phases of intrauterine and extrauterine growth and to examine the ability of the organism to adapt to these influences. We have proposed specific model systems for investigation. Investigation of specific enzymes and complex proteins as well as their control systems will be used to provide information concerning the many biochemical changes in various organs that accompany cellular differentiation and function. The effect of foodstuffs and oxygen will be examined as examples of external environmental stimuli which affect the growth of fetus and infant. The methodology will be primarily biochemical and physiological with particular emphasis on time-dependent systems. We conceive that the various environments to which the growing organism is exposed, from fertilized egg to newborn child, will determine his biological capabilities as an adult. This investigative program is constructed to consider these various stages of the life cycle of man in relation to environmental stimuli.